Manual Focus (Portraits)

[BogdanD]

I have an XSI, and usually use the 50mm f/1.8 mkii lens for portraits. One thing that's been bothering me lately is that I always have to use manual focus when doing portraits, which really turns out to be hit and miss. Autofocus just never gives me sharp photos. Is it because of the lens that I have to use manual focus? I know that using an aperture like 1.8 is going to give me a shallow DOF and therefore make it harder to focus on a precise area, but I have to manual focus even when the aperture is set to f/5.6 to get a sharp photo. Is this normal?

http://www.flickr.com/photos/48939759@N07/4907065533/


Above is a link to a picture I particularly like; it was just a fluke that I focused well.

[DavidEccleston]

Our focuses, on the next rebel up, the T1i. It's hard to tell at f/1.8 because of potential camera and subject movement, and softness wide open, but at f/2.2-f/2.5 or so, it's great. Are you choosing an appropriate focus point, or attempting to focus and recompose? Recomposing doesn't work well with a thin DOF.

[BogdanD]

I don't recompose, I just stay in one place and try to get the same picture but focused differently until it's sharp (at the eyes).

[DavidEccleston]

This is a crop from the first 50mm shot I found while digging around. It's a 100% crop taken at f/3.2.





I'm having a hard time finding a shot wider than 3.2 that isn't hampered by the fact that it was really dark and we used ISO-3200 as well...

[loveglory]

Wao, Its damn closeup with sharp quality.

[MattG]

The 50 1.8 is probably the cheapest lens you can buy these days. Are these fairly new purchases or are they a few years old. I wonder if the focusing machanisms are just worn and are no longer in sync? The review of the lens on this site was not to favourable but it does state:


The Canon EF 50mm f/1.8 II Lens' strongest quality is its sharpness. Sharpness performance wide open (f/1.8) is decent, but the Canon 50 f/1.8 is very sharp at f/2.8 and beyond. It is slightly sharper than even then Canon EF 24-70mm f/2.8 L USM Lens.


You would think you should be getting decent shots. Just not sure why you would use a lens of that quality on a 7D or 5D [:P]


MattG

[Daniel Browning]

My 50mm f/1.8 front-focused by a mile. If you get a body with microadjustment that might solve the problem.

[Sheiky]

Ouch, manual focussing with a 50mm 1.8 [^o)]

I have to manual focus even when the aperture is set to f/5.6 to get a sharp photo. Is this normal?

No it is not normal. While the auto-focus motor isn't the fastest available, you should have good autofocus results. Or your lens might suffer from front- or backfocus. In other words, it always focus just in front or to the back of the area you'd like it to focus on.


At f1.8 your lens is not the sharpest, so it's hard to judge if your lens focusses correctly at f1.8. However you could do the testing at f2.8 or so where the lens should be pretty sharp.


If your lens exhibits focussing-errors there are two things you can do. Send it back to Canon to recalibrate (if it's worth it) or buy a camera with micro-adjustment so you can compensate for the front- or backfocus.


Hope that helps,


Jan


Ps: I like the picture [Y][]

[Fifdy Cents]

I think it's a good idea to use a medium format camera for people
pictures. I use a Pentax 645 with a 150 lens often. I do 100% black
and white because I do it myself. I like having proof sheets that are
viewable and 15 shots is economical but still greatly superior to 35 mm
for portraits.

[BogdanD]

Thanks for the tips! I don't think I'll send it back to Canon because they'll probably charge me more than the thing is worth. [:P]